*2.1.1. Reagents*

Acetic anhydride (99%), maleic anhydride (96%), phthalic anhydride (99%), succinic anhydride (97%), and aminopropyltriethoxysilane (APS) (97%) were purchased from Sigma-Aldrich and used without further purification. The other analytical grade reagents were obtained from Merck (Brazil) and were used as received. The used motor oil used in this study was obtained from Retifica del Rei (São João del Rei, MG, Brazil). SB was supplied by Cachaça Coqueiro (Nazareno, MG, Brazil). The bagasse was washed repeatedly with distilled water to remove all the dirt particles. The washed fiber was then dried in an oven (Q314M, Quimis) at 60°C for 24 h under a flow of air. It was subsequently ground and sieved through 30 mesh sieves (TE648, Tecnal). The resulting natural fiber was designated as SBN and was used as the starting material to produce the modified SB.

### *2.1.2. Fiber modification*

In spite of crude oil sorption favored by hydrophobic surface, in the case of used motor oil, this behavior is not completely precise. The crude oil and fresh motor oil composition is based on a mixture of hydrocarbons, and hence present affinity for hydrophobic sorbent. However, the composition of used motor oil has been changed through thermal degradation and contamination from generated waste in the engine. This process leads to the formation of lowmolecular weight compounds and oxidation products [43]. Recently, Guilharduci et al. [44] showed that introduction of hydrophilic groups on SB improve the oil sorption from engine washing wastewater. Besides, it was also verified that surfactant present in wastewater affect

**Sorbent/treatment Sorption** 

Coir fiber (*Cocos nucifera*) 1.8–5.4 Sponge-gourd (*Luffa cylindrica*) 1.9–4.6

acid

acid

Acetylated with acetic anhydride

Raw cotton 30.5 [36]

Mangrove barks Untreated bark 1.666 [37] Treated with oleic

Treated with palmitic

Acetylated with acetic anhydride

Sugarcane bagasse modified with acetic anhydride 13.5–20.2 [38]

Sugarcane bagasse 6.65 [39]

Crude oil in dry conditions *Dacryodes edulis* leaf Unmodified leaf 3.440 [33]

Crude oil in distilled water Sisal (*Agave sisalana*) 3.0–6.4 [28]

Machine oil in distilled water Sugarcane bagasse Untreated bagasse 8.9 [35]

Motor oil in water Natural wood fibers 33–43 [40] Wastewater of used motor oil Natural wood fibers 5.56 [41]

Engine oil in dry conditions *Ceiba pentandra* (L.) Gaertn. fibers (Kapok) packing density 0.02 g mL−1)

**capacity (g g−1)**

4.990

3.333

3.333

11.4–16.5

50.8

47.4 [42]

**References**

The biomass acylation is well established in the literature, and the method is based on the reaction of hydroxyl groups (−OH) of the fiber surface with acyl groups (RCO–). Considering that the reaction with fiber is a heterogeneous reaction, not all hydroxyl groups is esterified,

the motor oil sorption.

**Adsorption/sorption** 

270 Sugarcane - Technology and Research

Crude oil in artificial

Synthetic effluent of crude

Used engine oil in dry

**Table 3.** Examples of oil sorption by biomass.

seawater

petroleum

conditions

**conditions**

Thermal treatment of SBN at 200°C for 24 h was performed to obtain the sample SB-200. The SBN acylation was obtained based on previous reports [44]. Briefly, the fiber was firstly soaked in 10% NaOH solution (using a ratio of 1 g/1 mL) at 0°C for 2 h. The bagasse was then washed with Milli-Q water until neutral pH and dried at 60°C for 24 h. Following this procedure, 70 g of the cleaned bagasse was placed in a 1 L round-bottom flask containing 300 mL of acylating agents and 200 mL of acetic acid. The mixture was acidified by adding 1 mL of H2 SO4 and maintained under agitation for 24 h at 60°C. At the end of this period, the solution was filtered and the product was rinsed first with ethanol and then with water until the pH reached around pH 7.0. After this procedure, the sample was dried at 60°C for 24 h. The acylating agents used were acetic anhydride, maleic anhydride, phthalic anhydride, and succinic anhydride, which produce the samples SB-Acet, SB-M, SB-P, and SB-S, respectively.

The procedure of SB silanization was based on previous report [44]. Basically, the SB is firstly washed with Milli-Q water at 60°C until no color was observed in the washed water, next the fibers are mixed with APS, using a 5/2 mass ratio of SBN/APS, and dispersed into 400 mL of acetone. The suspension was placed in a bottle with glass spheres and left on a roller-conveyor (TE500/1, Tecnal) for 24 h at 200 rpm. The excess of reagents were Soxhlet-extracted with acetone for 24 h. Subsequently, the fiber was dried in an oven at 60°C for 24 h, under a flow of air. The result sample was denominated as SB-APS.

#### *2.1.3. Fibers characterization*

Fourier transform infrared (FTIR) spectra were obtained in the range 400–4000 cm−1, using a Perkin-Elmer 1720 FTIR spectrometer. The samples were mixed with KBr (Merck, spectroscopy grade) in an approximate ratio of 10/1. The resulting mixture was pressed into pellets and the spectra were acquired using 300 scans with resolution of 4 cm−1. Determination of C and N contents was carried out with a Thermo Fisher Scientific, Flash 2000 Analyzer.

#### *2.1.4. Sorption experiments*

Sorption test was performed using a synthetic used motor oil/water mixture with an oil concentration of 10.0 g L−1. The used motor oil sorption was determined by immersing 1.0 g of fiber in 100 mL of the solution of oil/water mixture. After 24 h, the sorbent was removed, and dried for 24 h at room temperature. The oil sorption was calculated using the following equation:

$$\mathbf{Q} = \frac{m\_f - m\_i}{m\_i} \tag{1}$$

The modification introduced on the SBN was evaluated by FTIR and results are shown in **Figures 3** and **4**. For SBN spectra, four peaks are clearly observed between 3600 and 3307 cm−1 characteristic of stretching vibration of hydroxyl groups, which are associated with lignocellulose structure. Upon acylation with acetic anhydride, the intensity of ─O─H absorption band decrease because of hydroxyl groups reduction after reaction. In the same region of spectra, for SB-M only a diffuse band, centered at 3387 cm−1, is observed, and can be associated to hydrogen bonding in the hydroxyl groups. Similar profile is observed for SB-P and SB-S, in which, it is possible to identify two peaks less intense, at around 3600 and 3186 cm−1, also attributed to hydrogen bonding in the hydroxyl groups. These results confirm the modification of surface, which decrease the free hydroxyl groups at fiber surface. Successful esterification can be supported by three important absorption band around 1736, 1367, and 1242 cm−1, correspondent to the stretching vibration of carbonyl groups (C═O), C─H stretching, and C─O stretching characteristic of ester molecules. These bands can be clearly observed for SB-Acet, SB-S, and SB-M, however, with less intensity for SB-P, which can be associated with

**N% C%**

Sugarcane Bagasse As Potentially Low-Cost Biosorbent http://dx.doi.org/10.5772/intechopen.72153 273

**Sample Treatment Elemental analysis**

SBN *In nature* 0.18 45.7 SB-200 24 h at 200°C 0.28 48.2 SB-Acet Modified with acetic anhydride *Not detected* 45.1 SB-M Modified with maleic anhydride 0.12 44.8 SB-P Modified with phthalic anhydride 0.14 46.1 SB-S Modified with succinic anhydride *Not detected* 43.1 SB-APS Modified with aminopropyltriethoxysilane 2.15 42.5

possible lower acylation obtained for this sample.

**Figure 3.** FTIR spectra of (a) SBN, (b) SB-Acet (c) SB-P, (d) SB-S, and (e) SB-M.

**Table 4.** SB-based sorbents produced in this study.

where Q is the oil sorption capacity (g/g), m<sup>f</sup> is the total mass of dry sorbent (g) after sorption, and mi is the mass of dry sorbent before sorption (g). The water sorption was determined by the same procedure but using only water.

The experiments of oil sorption were also carried out in solutions containing sodium dodecylbenzenesulfonate in a proportion of 0.05–0.30% in the dispersion of used motor oil/water. The surfactant concentration was determined following the methodology established by the American Public Health Association (Water Environment Federation & APHA 2005).

#### **2.2. Results and discussion**

**Table 4** summarizes the samples prepared in this study. Results from elemental analysis of nitrogen and carbon in each sample are also presented in **Table 4**. It is noticed that the highest content of nitrogen obtained for SB-APS in relation to SBN fiber, which is attributed to amino groups from APS.


**Table 4.** SB-based sorbents produced in this study.

24 h. The acylating agents used were acetic anhydride, maleic anhydride, phthalic anhydride, and succinic anhydride, which produce the samples SB-Acet, SB-M, SB-P, and SB-S,

The procedure of SB silanization was based on previous report [44]. Basically, the SB is firstly washed with Milli-Q water at 60°C until no color was observed in the washed water, next the fibers are mixed with APS, using a 5/2 mass ratio of SBN/APS, and dispersed into 400 mL of acetone. The suspension was placed in a bottle with glass spheres and left on a roller-conveyor (TE500/1, Tecnal) for 24 h at 200 rpm. The excess of reagents were Soxhlet-extracted with acetone for 24 h. Subsequently, the fiber was dried in an oven at 60°C for 24 h, under a flow of

Fourier transform infrared (FTIR) spectra were obtained in the range 400–4000 cm−1, using a Perkin-Elmer 1720 FTIR spectrometer. The samples were mixed with KBr (Merck, spectroscopy grade) in an approximate ratio of 10/1. The resulting mixture was pressed into pellets and the spectra were acquired using 300 scans with resolution of 4 cm−1. Determination of C

Sorption test was performed using a synthetic used motor oil/water mixture with an oil concentration of 10.0 g L−1. The used motor oil sorption was determined by immersing 1.0 g of fiber in 100 mL of the solution of oil/water mixture. After 24 h, the sorbent was removed, and dried for 24 h at room temperature. The oil sorption was calculated using the following

*mi*

is the mass of dry sorbent before sorption (g). The water sorption was determined by

The experiments of oil sorption were also carried out in solutions containing sodium dodecylbenzenesulfonate in a proportion of 0.05–0.30% in the dispersion of used motor oil/water. The surfactant concentration was determined following the methodology established by the

**Table 4** summarizes the samples prepared in this study. Results from elemental analysis of nitrogen and carbon in each sample are also presented in **Table 4**. It is noticed that the highest content of nitrogen obtained for SB-APS in relation to SBN fiber, which is attributed to amino

American Public Health Association (Water Environment Federation & APHA 2005).

is the total mass of dry sorbent (g) after sorption,

(1)

and N contents was carried out with a Thermo Fisher Scientific, Flash 2000 Analyzer.

respectively.

272 Sugarcane - Technology and Research

*2.1.3. Fibers characterization*

*2.1.4. Sorption experiments*

equation:

and mi

air. The result sample was denominated as SB-APS.

*<sup>Q</sup>* <sup>=</sup> *mf* \_\_\_\_\_ <sup>−</sup> *mi*

where Q is the oil sorption capacity (g/g), m<sup>f</sup>

the same procedure but using only water.

**2.2. Results and discussion**

groups from APS.

The modification introduced on the SBN was evaluated by FTIR and results are shown in **Figures 3** and **4**. For SBN spectra, four peaks are clearly observed between 3600 and 3307 cm−1 characteristic of stretching vibration of hydroxyl groups, which are associated with lignocellulose structure. Upon acylation with acetic anhydride, the intensity of ─O─H absorption band decrease because of hydroxyl groups reduction after reaction. In the same region of spectra, for SB-M only a diffuse band, centered at 3387 cm−1, is observed, and can be associated to hydrogen bonding in the hydroxyl groups. Similar profile is observed for SB-P and SB-S, in which, it is possible to identify two peaks less intense, at around 3600 and 3186 cm−1, also attributed to hydrogen bonding in the hydroxyl groups. These results confirm the modification of surface, which decrease the free hydroxyl groups at fiber surface. Successful esterification can be supported by three important absorption band around 1736, 1367, and 1242 cm−1, correspondent to the stretching vibration of carbonyl groups (C═O), C─H stretching, and C─O stretching characteristic of ester molecules. These bands can be clearly observed for SB-Acet, SB-S, and SB-M, however, with less intensity for SB-P, which can be associated with possible lower acylation obtained for this sample.

**Figure 3.** FTIR spectra of (a) SBN, (b) SB-Acet (c) SB-P, (d) SB-S, and (e) SB-M.

other contaminants. Therefore, the presence of polar amino end groups (NH2

resulting in decreased adsorption capacity.

sorbent of wastewater of used motor oil.

The results are summarized in **Figure 6**(**a**, **b**).

structure favors the interaction with the constituents of the used motor oil. In contrast, the acylation of SBN was not effective to improve affinity with the constituents of used motor oil

In spite of the higher oil sorption obtained for SB-APS (0.71 g g−1) in relation to SBN (0.60 g g−1), the difference was about 15%, which is relatively small. It is important to take in account that the fiber modification with silane groups is a costly and complex process. Considering the abundance, low cost and efficiency of SBN, this material presented the best cost benefit for use as

Previous studies showed that the surfactants in used motor oil wastewater can affect its sorption by natural fibers [44]. Surfactants are widely used in various industrial processes for oil recovery, because of their physicochemical characteristics for emulsification, dispersion, and solubilization [48]. They have the ability to reduce the oil-water interfacial tension, increase the capillarity, and change the wettability of the adsorbent surface. Then, in order to evaluate the impact of surfactants on the SBN sorption capacity, batch experiments were carried out using an anionic surfactant, sodium dodecylbenzenesulfonate, in a dispersion of oil (1.0 g)/water (0.1 L).

**Figure 6.** (a) The effect of anionic surfactant in the oil sorption and (b) surfactant sorption in dispersion with and without oil.

) from silane

275

Sugarcane Bagasse As Potentially Low-Cost Biosorbent http://dx.doi.org/10.5772/intechopen.72153

**Figure 4.** FTIR spectra of (a) SBN and (b) SB-APS.

For sample SB-APS, the FTIR is very similar to SBN (**Figure 4**). The characteristics of absorption bands of ─Si─O─Si─ at 700, 1030, 1145, and 1187 cm−1 overlapping with groups present in the biomass surface hinder its identification [47]. However, in the region of 3600–3000 cm−1, the APS modification leads to emerging of strong band, centered at 3398 cm−1, attributed to hydrogen bonding from hydroxyl groups. This behavior suggesting that hydrophilic groups (─NH2 ) from APS could be interacting with free hydroxyl groups.

The effect of SB modifications over oil and water sorption capacity can be observed in **Figure 5**. It is possibly observed that samples SB-APS, SBN, and SB-200 show higher affinity with water and also with used motor oil. This result suggests that the introduction of hydrophilic groups on SBN improve the used motor oil sorption. Guilharduci et al. [44] showed that used motor oil presents more affinity to hydrophilic surface than for crude oil. As previously discussed in the introduction, this behavior can be attributed to the chemical differences between used motor oil and new motor oil. Used motor oil can contain sludge, metal residues, and various

**Figure 5.** Oil and water sorption capacity for SB samples.

other contaminants. Therefore, the presence of polar amino end groups (NH2 ) from silane structure favors the interaction with the constituents of the used motor oil. In contrast, the acylation of SBN was not effective to improve affinity with the constituents of used motor oil resulting in decreased adsorption capacity.

In spite of the higher oil sorption obtained for SB-APS (0.71 g g−1) in relation to SBN (0.60 g g−1), the difference was about 15%, which is relatively small. It is important to take in account that the fiber modification with silane groups is a costly and complex process. Considering the abundance, low cost and efficiency of SBN, this material presented the best cost benefit for use as sorbent of wastewater of used motor oil.

Previous studies showed that the surfactants in used motor oil wastewater can affect its sorption by natural fibers [44]. Surfactants are widely used in various industrial processes for oil recovery, because of their physicochemical characteristics for emulsification, dispersion, and solubilization [48]. They have the ability to reduce the oil-water interfacial tension, increase the capillarity, and change the wettability of the adsorbent surface. Then, in order to evaluate the impact of surfactants on the SBN sorption capacity, batch experiments were carried out using an anionic surfactant, sodium dodecylbenzenesulfonate, in a dispersion of oil (1.0 g)/water (0.1 L). The results are summarized in **Figure 6**(**a**, **b**).

For sample SB-APS, the FTIR is very similar to SBN (**Figure 4**). The characteristics of absorption bands of ─Si─O─Si─ at 700, 1030, 1145, and 1187 cm−1 overlapping with groups present in the biomass surface hinder its identification [47]. However, in the region of 3600–3000 cm−1, the APS modification leads to emerging of strong band, centered at 3398 cm−1, attributed to hydrogen bonding from hydroxyl groups. This behavior suggesting that hydrophilic groups

The effect of SB modifications over oil and water sorption capacity can be observed in **Figure 5**. It is possibly observed that samples SB-APS, SBN, and SB-200 show higher affinity with water and also with used motor oil. This result suggests that the introduction of hydrophilic groups on SBN improve the used motor oil sorption. Guilharduci et al. [44] showed that used motor oil presents more affinity to hydrophilic surface than for crude oil. As previously discussed in the introduction, this behavior can be attributed to the chemical differences between used motor oil and new motor oil. Used motor oil can contain sludge, metal residues, and various

) from APS could be interacting with free hydroxyl groups.

**Figure 5.** Oil and water sorption capacity for SB samples.

(─NH2

**Figure 4.** FTIR spectra of (a) SBN and (b) SB-APS.

274 Sugarcane - Technology and Research

**Figure 6.** (a) The effect of anionic surfactant in the oil sorption and (b) surfactant sorption in dispersion with and without oil.

The used motor oil sorption shows slight increase (13%) in low concentration of surfactant, and afterward, the sorption decreases almost 42%. When the surfactant concentration increases, the hydrophobicity of fiber in aqueous solution decreased as a result of lower interfacial energy between water and fibers. In parallel, the oil-water interface is improved although micelles or microemulsions formation, which probably affects the oil sorption by SBN and improve surfactant interaction with the fiber. In this condition, the surfactant sorption is likely increased by SBN surface. This suggestion can be evaluated by the analyses of surfactant sorption in the water dispersion with and without oil. The results of these experiments are depicted in **Figure 6(b)**. Based on this result, it is noticed that surfactant sorption not only increases when its concentration increases but also is enhanced in the oil/water dispersion.

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